Adenylosuccinate lyase deficiency

Adenylosuccinate lyase deficiency
Adenylosuccinate lyase deficiency has an autosomal recessive pattern of inheritance
Classification and external resources
ICD-9-CM	277.2
OMIM	103050
DiseasesDB	33422
MeSH	C538235
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Adenylosuccinate lyase deficiency, also called adenylosuccinase deficiency, is a rare autosomal recessive metabolic disorder characterized by the appearance of succinylaminoimidazolecarboxamide riboside (SAICA riboside) and succinyladenosine (S-Ado) in cerebrospinal fluid, urine.These two succinylpurines are the dephosphorylated derivatives of SAICA ribotide (SAICAR) and adenylosuccinate (S-AMP), the two substrates of adenylosuccinate lyase (ADSL), which catalyzes an important reaction in the de novo pathway of purine biosynthesis. ADSL catalyzes two distinct reactions in the synthesis of purine nucleotides, both of which involve the β-elimination of fumarate to produce aminoimidazole carboxamide ribotide (AICAR) from SAICAR or adenosine monophosphate (AMP) from S-AMP.

Among the signs and symptoms of adenylosuccinate lyase deficiency are the following:

Adenylosuccinate lyase deficiency is responsible for a range of symptoms that involve psychomotor retardation, often accompanied by epileptic seizures, and autistic features. Two common theories were proposed to account for these effects, the first is that they result from decreased concentrations of purine nucleotides needed for purine biosynthesis. Decreased concentrations, however, could not be found in various tissues taken from ADSL-deficient people, probably because purines are furnished via the purine salvage pathway. The second is the buildup of accumulating succinylpurines causes neurotoxic effects. In the severely affected individuals, the concentration levels of SAICA riboside and S-Ado are comparable, whereas in people with milder forms of the disease, the ratio of S-Ado is more than double that of those more severely affected, while SAICA riboside concentration levels remain comparable.

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